1. Field of the Invention
The present invention relates to an electronic device and a lens module thereof. More particularly, the present invention relates to an electronic device having shorter main shaft and an optical zoom lens module thereof.
2. Description of Related Art
Nowadays, in addition to communicating with each other, the mobile phone device has such functions as sending/receiving SMS and e-mails, playing radio and MP3 music, and taking photos. Especially the camera function which can be used for taking photos instantly is popular among young consumers. A mobile phone having camera function is because that an imaging device for capturing image of an object is disposed in the mobile phone device. The imaging device is mainly composed of an optical zoom lens module and a photosensitive device, and the image of an object is focused on the photosensitive device through the optical zooming of the optical zoom lens module.
FIG. 1A is a diagram of a conventional optical zoom lens module at 2× optical zoom. Referring to FIG. 1A, the conventional optical zoom lens module 100 includes two “” shape lens holders 122 and 124 disposed on a main shaft 110, and two lenses 132 and 134 respectively held by the lens holders 122 and 124. When the optical zoom lens module 100 is at 2× optical zoom, the lens 132 is close to the lens 134, and the two lens holders 122 and 124 are in contact with each other and two spans are formed. Since the spans take up part of the height of the main shaft 110, the spans are one of the major factors for designing the height of the main shaft 110 to prevent insufficient moving distance of the lens holders 122 and 124 caused by insufficient height of the main shaft 110, which may affect the effect of optical zooming.
FIG. 1B is a diagram of the optical zoom lens module in FIG. 1A at 1× optical zoom. Referring to FIG. 1A and FIG. 1B together, when the optical zooming multiple of the optical zoom lens module 100 is adjusted, the positions of the lenses 132, 134 and the relative distance between the lens 132 and 134 are adjusted by moving the lens holders 122 and 124 at the same time. As shown in FIG. 1B, when the optical zoom lens module 100 is at 1× zoom, the lens 132 is away from the lens 134, however, one end of the lens holder 122 and one end of the lens holder 124 are still in contact to form a span which takes up the height of the main shaft 110. As described above, when designing the height of the main shaft 110 of the conventional optical zoom lens module 100, the span formed by the two lens holders 122 and 124 has to take into consideration besides the zooming interaction distance of the lenses 132 and 134 accordingly, so that the thickness of the entire mobile phone device is affected.